Most of catalysts for olefin polymerization are prepared by supporting a titanium halide on an active magnesium chloride. A common method used to prepare the active magnesium chlorides is to react anhydrous MgCl2 with an alcohol to form a magnesium chloride-alcohol adduct of general formula: MgCl2.mROH.nH2O. Then, a titanium halide is supported on such an adduct to afford a solid catalyst component for olefin polymerization. Such alcohol adducts may be prepared by known processes, such as spray drying process, spray cooling process, high-pressure extruding process, or high-speed stirring process. See, for example, U.S. Pat. Nos. 4,421,674, 4,469,648, WO8707620, WO9311166, U.S. Pat. Nos. 5,100,849, 6,020,279, 4,399,054, EP0395383, U.S. Pat. Nos. 6,127,304 and 6,323,152.
Other magnesium-containing complex carriers useful in the preparation of catalysts for olefin polymerization are also known in the art. For example, CN102040681A discloses a compound that can be used as a carrier of catalysts for olefin polymerization, having a structure of:
wherein R1 is a C1-C12 linear or branched alkyl; R2 and R3 are identical or different, and are independently hydrogen or unsubstituted or halogen-substituted C1-C5 linear or branched alkyl; X's are chlorine or bromine, and one of the X's may be C1-C14 alkyl, C1-C14 alkoxy, C6-C14 aryl or C6-C14 aroxy; m is in a range of from 0.1 to 1.9, n is in a range of from 0.1 to 1.9, and p+m+n=2. Said compound is prepared as follows: MgX2 reacts with an alcohol of general formula R1OH in the presence of an inert dispersion medium at 30 to 160° C., to form a magnesium halide-alcohol adduct solution; then the solution reacts with an oxirane compound at 30 to 160° C., to form the magnesium compound useful as a carrier, wherein X is chlorine or bromine, R1 is a C1-C12 linear or branched alkyl. CN102040680A also discloses an olefin polymerization catalyst, which is prepared by using said compound useful as a carrier of olefin polymerization catalyst disclosed in the above-mentioned patent application.
There is still need to a magnesium-containing complex or spherical carrier that can be used in the preparation of a catalyst component for olefin polymerization and a method by which such a magnesium-containing complex or spherical carrier can be simply, effectively, and low-costly prepared. There is also still need to a catalyst component for olefin polymerization that exhibits desired properties, such as high activity and high stereo-directing ability.